In French, we use the term exercice to refer to a period of time between two events. We say exercice fiscal for fiscal year, exercice comptable for accounting period, etc. One of the senses given by the online monolingual Larousse French dictionary for this word is:

So it means the entire period spanning two accounting inventories or two budgets. (The parenthesized portion merely explains how in France, the twelve-month accounting year need not correspond to the calendar year.)

Can you use the same term exercise with this same meaning in English as well?

Look up the English word "exercise". If you use "exercice" it will be read as a misspelling of "exercise". Confusion will result.
– Hot LicksSep 14 '18 at 11:59

Look in an English dictionary and see if your usage of exercise is there. I have never heard of "fiscal exercise" or "accounting exercise" meaning a period of time. But don't believe me, believe your dictionary.
– GEdgarSep 14 '18 at 12:13

2

Welcome to EL&U. As the other commenters have noted, one of the expectations of Stack Exchange is that you demonstrate some initial research attempts; there are zero overlapping definitions of exercise in common usage that would permit its use as you describe. Period or term would be the most common equivalent, e.g. reporting period, academic term.
– chosterSep 14 '18 at 15:59

Interestingly, Spanish also has this same ‘economic’ sense for their cognate of this word, and one of the examples given for it is even ejercicio fiscal, just like yours. But I have been unable to trace when this sense for it entered either French or Spanish. Perhaps this specialized sense occurred later than when Middle English first imported the noun from French during the 14th century, but it is curious that it exists in both French and Spanish yet not — as far as I can see — in English. Maybe Spanish borrowed the new sense at some point.
– tchrist♦Sep 17 '18 at 1:20